Guarana is a dietary supplement made from the seeds of a South American tree.
It is high in caffeine and is taken by some people as an energy supplement.
Health claims about food products in the EU are regulated by the European Food safety Authority (EFSA). It rejected a claim that extract of guarana (Paullinia cupana) is a natural antioxidant, which may protect against oxidative damage and is beneficial to human health.
Researchers once believed that the active ingredient of guarana was a chemical specific to the plant - guaranine. They later discovered that it was just caffeine. Guarana has some of the highest concentrations of caffeine in any plant. It may contain up to 6% to 7% caffeine by weight. Coffee only has up to 2%.
Research shows coffee and other caffeinated beverages seem to increase alertness when consumed throughout the day and guarana would logically have the same effect. Some studies have looked into whether caffeine can improve mental performance and alertness in sleep-deprived people, but results are inconclusive.
Experts have not studied guarana extensively. So far, studies have not found that guarana is helpful for improving cognitive ability or mood. Some people use guarana to boost athletic or sexual performance but there’s no evidence to back this up.
There’s some evidence, published in the International Journal of Obesity, that guarana - when used along with other supplements - may promote weight loss, but it’s uncertain if the guarana specifically was responsible. A 2001, an 8 week randomised study of a herbal supplement containing guarana concluded the mixture “effectively promoted short term weight loss”. Because caffeine is a stimulant that has been shown to improve mood and possibly aid weight loss, guarana may very well also have these effects, but more research is needed. As a weight loss supplement, caffeine may work best when combined with the polyphenol compounds in green tea. Combining guarana with polyphenols may have a similar effect.
Some believe that the effects of guarana are less intense and longer-lasting than caffeine. Studies have not established this.
Guarana dose and instructions for use
There is no standard dose of guarana. Ask your GP for advice.
Guarana food sources
Besides the guarana seed itself, there are no natural food sources of guarana. It has become a common additive to some foods and drinks.
Guarana supplement information
Guarana may come in tablets or capsules or as an additive in foods and drinks. As with any supplement, keep guarana in a cool, dry place, away from humidity and direct sunlight.
- Side effects. The side effects of guarana are generally the same as the side effects of caffeine. They include sleep problems, anxiety, restlessness, upset stomach and quickened heartbeat. Long-term use of caffeine may result in tolerance and psychological dependence.
- Risks. High doses of caffeine may raise the risk of increased heart rate, breast disease and high blood pressure. An overdose of caffeine can cause seizures and convulsions. Talk to your GP before using guarana if you have high blood pressure, anxiety disorders, glaucoma, osteoporosis, heart problems, bleeding disorders, diabetes, kidney problems or liver disease.
- Interactions. If you take any medications regularly, talk to your GP before you start using guarana supplements because they could interact with medicines like some antidepressants, lithium, sedatives and blood thinners. Don’t use guarana along with other stimulants, whether they’re medications, supplements or illegal drugs. To avoid excessive caffeine intake, be careful when taking guarana along with other foods and supplements that contain it, like coffee and fizzy drinks.
Given the lack of evidence about its safety - and because of its high caffeine content - guarana is not recommended for children or for women who are pregnant or breastfeeding.